Removable cover for current limiting fuse housing



A ril 17, 1962 w. M. SCOTT, JR 3,030,474

REMOVABLE COVER FOR CURRENT LIMITING FUSE HOUSING Filed Feb. 20, 1959 5 Sheets-Sheet 1 INVENTOR. Will/AM M- 560/7 I6. 7

sYgljd JAM/ W. M. SCOTT, JR REMOVABLE COVER FOR CURRENT LIMITING FUSE HOUSING April 17, 1962 Filed Feb. 20, 1959 3 Sheets-Sheet 2 INVENTOR. W/zZM/v M 5:07; Jae.

QZ: 4 M, 4142 9- Aff O April 17, 1962 w. sco JR 3,030,474

REMOVABLE COVER FOR CURRENT LIMITING FUSE HOUSING Filed Feb. 20, 1959 3 Sheets-Sheet 3 938 8/ 2| [L 9 I 32 1 Q5 37 INVENTOR.

Will/AM M. scoff JP.

BYQZAZIJ,VI 1M United States Patent O 3,030,474 REMOVABLE CDVER F R CURRENT LIMITING FUSE HOUSING William M. Scott, Jr., Bryn Mawr, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed Feb. 20, 1959, Ser. No. 794,667 4 Claims. (Cl. 200-133) My invention relates to a novel cover for current limiting fuse housings in which the rating of the current limiting fuses is continuously observable, and in which a removable cover plate allows rapid inspection of a housing containing a plurality of current limiting fuses to determine which of the fuses has been operated, or the condition of the fuses at any time without removing the fuses from service.

Current limiting fuse housings are well known in the art particularly in their use with circuit breakers where the current limiting fuses are electrically and mechanically coordinated with the circuit breakers, as set forth in copending application Serial No. 622,042, filed November 14, 1956, now Patent No. 2,924,688, entitled End Mounting of a Current Limiting Device Associated With a Circuit Breaker, in the name of William Harold Edmunds and assigned to the assignee of the present invention.

As will be seen by reference to the above noted application, each current limiting fuse within the housing is provided with a means which is actuated responsive to the operation of the fuse to cause the circuit breaker to operate. In multiphase circuits, in order to find out which phase was faulted and, thus, cause a combined circuit interrupter to operate, it has been necessary first to completely remove the fuse housing from the circuit breaker by mechanically and electrically disconnecting the units. In a like manner, if it is necessary to make sure that a fuse of a given rating is being used in the combined circuit interrupter, it has been necessary to completely disconnect the unit and remove the fuses to see the rating marked on the fuses.

The essence of this invention is to construct the externally accessible cover of the fuse housing with a plurality of apertures aligned with the operating means of each of the fuses, and with a further aperture aligned with a portion of at least one fuse which indicates the rating of the fuse. The apertures so placed in the housing cover may then be sealed by a cover plate means which is snapped in place by a locking wire or bale. Accordingly, if it is now desired to check the rating of the fuses of a particular fuse housing, or to see which phase caused a circuit interrupter operation, or to merely determine the condition of the fuses, the top plate member is easily and simply removed, and visual observation through the apertures is made.

It will be noted that this can be done without disconnecting the fuses from their circuit, either mechanically or electrically, so that when checking the fuse rating, or the general condition of the fuses, it is not necessary to open the circuit being protected by the interrupter.

However, if it is desirable to assure that when the cover plate is removed, that there is no exposure to dangerous voltages, the cover plate may be interlocked with the circuit breaker trip mechanism so that the breaker is automatically tripped when the plate is removed.

Accordingly, the primary object of my invention is to provide a novel cover for a current limiting fuse housing.

Another object of my invention is to provide a novel in which the rating of the fuses and the condition of the 3,039,474 Patented Apr. 17, 1962 fuses may be observed without disconnecting the fuses from their terminals.

Another object of my invention is to provide a novel cover structure which can give a continuous indication of fuse rating for fuses positioned below the cover.

Another object of my invention is to provide a novel removable cover plate for a current limiting fuse housing in which removal of the cover plate exposes the actuating means of the fuses contained within the housing.

These and other objects of my invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE 1 is a perspective view of a current limiting fuse housing which is connectable to the base of a circuit breaker, and indicates the manner in which the cover plate of the current limiting fuse housing is connected.

FIGURE 2 is an exploded perspective of the current limiting fuse housing of FIGURE 1, and illustrates the manner in which the removable plate portion cooperates With the cover of the fuse housing.

FIGURE 3 shows a top view of the current limiting fuse housing with the plate removed.

FIGURE 4 shows a top view similar to FIGURE 3 with the plate in its connected position.

Referring now to FIGURE 1, the figure shows a structure which, for the exception of the cover structure, is fully described in the above noted copending application Serial No. 622,042.

Generally, a circuit breaker housing 20 is provided which has an extending base portion 21 which may be either an integral part of the circuit breaker 20 or may be a removable base portion. Contained within circuit breaker housing 20 is an operating mechanism of any desired type, such as that shown in US. Patent No. 2,574,- 093 to William Harold Edmunds wherein operating handle 30 operates a pair of contacts for each phase of the three-phase circuit breaker illustrated in FIGURE 1. Contacts of each phase are then terminated by disconnect contacts 31, 32 and a contact 33 which is not seen in FIGURE 1.

The extension 21 of FIGURE 1 carries additional disconnect contacts 34, 3'5 and 36 which cooperate with contacts 31, 32 and 33 respectively for connecting a current limiting fuse in series with each of the respective circuit breaker phases. Each of disconnect contacts 31 through 36 are of the tulip-clip type, such as that described in copending application Serial No. 536,586 filed September 26, 1955 and assigned to the assignee of the present invention, and are constructed to receive a stud in electrical and mechanical engagement. However, for purposes of the present invention, disconnect contacts 31 through 36 could be of any desired type.

Current limiting devices for cooperating with each of the circuit breaker phases are housed within housing 37. FIGURE 2 more specifically shows these current limiting devices as fuses 38, 39 and 40 which are provided with disconnect studs 41-42, 4344, and 4546 respectively. As seen in FIGURE 1, fuse 40 is connected to its corresponding phase by connection of disconnects 41 and 42 and disconnects 36 and 33 respectively. In a similar manner, disconnects 43, 44 and 45, 46 of FIGURE 2 will cooperate with disconnects 35, 32 and 34, 31 respectively of FIGURE 1.

Fuses 38, 39 and 40 are maintained in housing 37 by retaining plate 47 which is fastened to housing 37 by screws 48 and 49 as seen in FIGURE 2 and described in copending application Serial No. 623,882 filed November 23, 1956, entitled, Spring Mounting of Current Limiting Devices Within a Housing in the name of William Harold Edmunds, and the assembled housing is connected to the circuit breaker housing by screws 50 and 51 which pass through apertures 52 and 53 respectively, and

3 intotapped openings 54 and 55 of extension 21 as seen in FIGURE 1.

As may be seen in the above noted copending application Serial No. 622,042, each of fuses 38, 39 and 40 are provided with astriker pin such as striker pin 85 of fuse 40 which is ejected from the fuse upon operation thereof. The .striker pins are positioned to pass through a .cooperating aperture, such as aperture 56 of disconnect .an operating member 62 of circuit breaker 20 by a biasing spring 63.

More specifically, in the normal condition, projection 61 Will bias operating member 62 inwardly so as to normally preventoperation of the circuit breaker 20. When,

however, there is a predetermined electrical condition which causes the current limiting fuse to operate, the striker pin of the fuse in the faulted phase will be ejected to engage either of projections 58, 59 or 64), and thus rotate auxiliary tripper bar 57 clockwise against the force of biasing spring 63, and release the trip means 62 of the circuit breaker, and thus cause operation of the circuit breaker.

It will be further noted in FIGURE 2 that each of current limiting fuses 38, 39 and 40 are provided with label means 65, 66 and 67, which labels give the rating of the fuses. Since, in the past, the upper cover of the housing 37 has been a solid member, it has been impossible to determine either the rating of the fuses being used in the housing, or which of the fuses has been operated responafter removing the fuses. This is an extremely inconvenient arrangement, and requires the disconnection of the energized line and thus interrupt service to a circuit in order to make this determination.

The essence of my invention is, as set forth above, to place apertures in the cover of the fuse housing, and thereafter covers these apertures with a simple plate means which can be easily removed from the housing.

In accordance with my invention, and, as best seen in FIGURES .2 and 3, the upper cover of housing 37 contains three openings 70, 71 and 72 which are in alignment with fuses 38, 39 and 40 respectively, to provide visual access to the condition of the striker pins of the respective fuses.

A further set of apertures 73, 74 and 75 of smaller size than apertures 70, 71 and 72 are placed in registry with the position of labels 65, 66 and 67 respectively. Apertures 73, 74 and 75 may, if desired, be open and continually exposed, or they may be provided with transparent inserts.

In order to receive a cover plate for closing apertures 70, 71 and 72, and, if desired, apertures '73, 74 and 75, the cover is further formed with protrusions such as protrusions 76, 77 and 78 having centrally located neckeddown portions therein, projections 79, 80 and the pair of projections 81 and 82.

The cover plate for the cover of FIGURES 2 and 3 is best seen in FIGURES 1 and 4 as plate 83. Plate 83 has two keyholes, 84 and 85 and two projecting ears 86 and 87 at either end. The keyholes 84 and 85 are positioned to cooperate with protrusions 77 and 78 of FIGURES 2 and 3, as seen in FIGURES 1 and 4, where the enlarged portion of the keyholes is larger than the greater diameter of protrusions 77 and 78, while the small width portion of keyholes 84 and 35 fits into the necked-down portions of their respective projection. To further position i and secure plate 83, a locking wire or bale 88 is carried by cars 86 and 87 and lies in a path defined by projections 81 and 82 and projection 80. The wire 88 is locked in place by positioning a bent portion 89 of the wire into the necked-down portion of projection 76 in the well known manner.

It will now be understood that the cover plate 83 is easily connected and removed from the cover of the current limiting fuse housing 37. Thus, it is only necessary to.

align keyholes 84 and with their corresponding projections 77 and 78 and then slide the cover to the left until the left-hand end of cover plate 83 engages projection 79. The wire or bale 88 is then rotated into the snap-in position shown in FIGURES 1 and 4. With the cover plate 83 in the position of FIGURES 1 and 4, it

will be noted that the rating of fuses 38, 39' and 40 may be continually observed through the windows 73, 74 and 75, since these windows are aligned with the rating labels.

If desired, however, the cover plate 83 could be extended so as to cover windows 73, 74- and 75, thus requiring an operator to first remove the cover before observing the rating of the units, and thus assuring a completely enclosed housing.

If it is now desired to observe the condition of the current limiting fuses, it is onlynecessary to depress wire or bale 88 out of the necked-down portion of projection 86, and then rotate the wire upwardly. This will permit the cover 83 to be moved to the right so that keyholes 84 and 85 may be removed from projections 77 and 78, and

the fuses may then be observed through windows 70, 71 and 72.

.It will be apparent that the wire or baie88 cannot only be used to move the cover plate 83 in its plane, but also can 'be used to remove the entire auxiliary housing arrangement 37. That is, when the bale or wire 88 is rotated from the position of FIGURES 1 or 2, a force applied thereto perpendicular to the removable plate 83 will result in the force being exerted on the disconnect contacts of the current limiting fuses, thereby removing the entire assembly comprised of the removable cover 83, the housing 37 and the current limiting fuses 38, 39 and 40.

The cover plate 83 could carry interlock means which are connected between the plate and the auxiliary tripper bar 57 of the fuse housing, so that a movement of the plate to the right when the plate is to be removed would cause operation of the tripper bar 57 and disconnection of the circuit breaker. This interconnection is schematically illustrated in FIGURE 2 by the dotted line from plate 83 to tripper bar ,57. Accordingly, when the plate 83 is removed to afford visual access to fuses 38, 39 and 40, the circuit breaker is automatically tripped so that the danger of reaching into the fuse housing and accidentally touching points of highpotential is eliminated.

If it is desired to prevent accidental slipping between the plate 83 and housing 37 while removing the housing by the bale 58, a holding down bolt may be further provided to connect the two where the bolt passes through a uniform width slot in plate 83 and is readily removable to permit subsequentremoval of the plate 83.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

I claim:

1. A current limiting fuse housing; said housing including a plurality of current limiting fuses; each of said current limiting fuses including visually observable means for indicating the operation of its respective current limiting fuse; each of said current limiting fuses including a label indicating the rating of its respective current limiting fuse; mounting means for rigidly retaining each of said current limiting fuses in position within said housing; said housing having a cover member; said cover member having a first plurality of apertures therein for affording visual access to a respective visually observable means of each of said current limiting fuses and a second plurality of apertures for affording visual access to a respective label of each of said current limiting fuses; and a cover plate, said cover plate being positioned to seal at least said first plurality of apertures in said cover member; said cover plate being removably connected to said cover member externally of said housing by keyed mounting means extending between said cover member and said cover plate and bale means mounted to said cover member for retaining said keyed mounting means in a locked condition; said bale means being operable between a first and a second position; said bale means when in said first position blocking removal of said cover plate from said cover and when in said second position permitting removal of said cover plate from said cover member; said bale means being operatively connected and positioned to permit removal of said cover plate from said cover member.

2. In combination; a plurality of current limiting fuses and a multiphase circuit breaker; each of said plurality of current limiting fuses being connected in series with a respective phase of said circuit breaker; said current limiting fuses being contained within a housing means; said current limiting fuses within said housing means being adapted to be plugged into their said series relation with said circuit breaker phases; each of said current limiting fuses having a striker pin and a rating label; said housing means having a cover; said cover having a plurality of apertures; at least one of said apertures being in registry with at least one of said current limiting fuse striker pins; at least another of said apertures being in re istry with at least one of said current limiting fuse rating labels; a cover plate; said cover plate being removably connected to said cover externally of said housing; said cover plate enclosing at least said first mentioned one of said apertures in registry with said current limiting fuse striker pin; said cover plate having means to disconnect said fuse housing from said multiphase circuit breaker.

3. In combination; a plurality of current limiting fuses and a multiphase circuit breaker; each of said plurality of current limiting fuses being connected in series with a respective phase of said circuit breaker; said current limiting fuses being contained within a housing means; said current limiting fuses Within said housing means being adapted to be plugged into their said series relation with said circuit breaker phases; each of said current limiting fuses having a striker pin and a rating label; said housing means having a cover; said cover having a plurality of apertures; at least one of said apertures being in registry with at least one of said current limiting fuse striker pins; at least another of said apertures being in registry with at least one of said current limiting fuse rating labels; a cover plate; said cover plate being removably connected to said cover externally of said housing; said cover plate enclosing at least said first mentioned one of said apertures in registry with said current limiting fuse striker pin; said cover plate having means to disconnect said fuse housing from said multiphase circuit breaker; removal of said cover plate allowing visual access to said striker pin in registry with said first mentioned aperture without removing said fuse housing from said circuit breaker.

4. In combination; a plurality of current limiting fuses and a multiphase circuit breaker; each of said plurality of current limiting fuses being connected in series with a respective phase of said circuit breaker; said current limiting fuses being contained within a housing means; said current limiting fuses within said housing means being adapted to be plugged into their said series relation with said circuit breaker phases; each of said current limiting fuses having a striker pin and a rating label; said housing means having a cover; said cover having a plurality of apertures; at least one of said apertures being in registry with at least one of said current limiting fuse striker pins; at least another of said apertures being in registry with at least one of said current limiting fuse rating labels; a cover plate; said cover plate being removably connected to said cover externally of said housing; said cover plate enclosing at least said first mentioned one of said apertures in registry with said current limiting fuse striker pin; and interlock means; said interlock means being operatively connected between the trip mechanism of said circuit breaker and said removable cover for automatically tripping said circuit breaker when said removable cover is removed.

References Cited in the file of this patent UNITED STATES PATENTS 1,927,157 Earle Sept. 19, 1933 2,059,987 Frank Nov. 3, 1936 2,756,303 Gilday July 24, 1956 2,888,535 Edmunds May 26, 1959 2,905,791 Edmunds Sept. 22, 1959 FOREIGN PATENTS 788,565 France July 29, 1935 576,297 Great Britain Mar. 27, 1946 

